You may also be given leucovorin, a drug used to help prevent or treat the side effects of methotrexate, by intravenous (IV) infusion through a catheter or port you have already had placed in your arm. If the study doctor thinks it is needed, this infusion will be given after each cycle to help with the possible side effects you may experience from methotrexate. The infusion should last about 5 minutes each time.